1. Field of the Invention
The invention relates to an apparatus for the removal of the skin of fillets of fish.
In the skinning of fish fillets on skinning machines of the construction principle in which a skinning roller driven to rotate is used, such roller normally includes a plurality of grooves extending parallel to the axis of rotation and defining a roller surface which is limited to the ridge faces of the webs separating two neighbouring grooves. In this type of skinning machine there is further made use of a presser face opposing said roller's circumferential surface, and of a skinning knife associated with said presser face. In such skinning apparatus structure it is important, on the one hand, to achieve a precise incision, i.e. to ensure that the skin of the fillet runs in between the skinning roller and the presser face and, on the other hand, to achieve that the skinning is accomplished with the least possible loss of fillet meat. The expert is able to recognise to what extent the latter requirement can be fulfilled on the basis of the quality of the so-called silver mirror which constitutes the layer between the meat and skin in the majority of the bulk fish types. Simultaneously, the flawless presence of this feature gives the fillet an appealing exterior, which is the reason that it is considered indicative of quality by the consumer.
As practice demonstrates, the coordination of these requirements is problematic because the appropriate steps for optimising the individual requirements, in accordance with current knowledge, runs counter to the respective remaining requirements.
2. Related Art
A typical piece of prior art for this kind of apparatus is represented through the disclosure of DE-AS 26 53 946, which shows a skinning apparatus of the type described above. The skinning roller, according to this concept, is provided with grooves on its circumferential surface which have, remaining between them, a tooth web which resembles saw teeth in cross-section. The grooves have a cross-section which is designed to enable the leading tip or end of the fillet to be skinned to arrive under the skinning knife and underneath the presser face.
In such an arrangement, to be observed is that the incision accuracy increases with greater tooth separation. The silver mirror, however, is simultaneously destroyed or lost.
Thus, another machine concept to be taken from DE PS 28 44 241 originated, in which a skinning roller is used which has a circumferential surface, the latter having simply been roughened and being interrupted by single grooves. These have, in an example, a width of 5 mm and a depth of 1.5 mm. Consequently, they are relatively flat and guarantee a precise incision. Although with a skinning roller of such design the desired silver mirror on the fillet is obtained in the regions between the grooves, it is reduced in the region of the grooves, according to the quality and kind of fish being processed, such that the position of the grooves can be recognised on the skinned fillet.